Possible Clues:

• 'Convict, detainee (8)'
• One in gaol
• Ripens or develops in the cell
• Sniper or butcher is detained
• Person of conviction
• Hostage to public relations? Is one right?
• Bad person, one put inside, right?
• Captive boy held hostage by intruder
• Jean Valjean, e.g.
• He's inside to see the one prying about your boy